Gas-fired water heater



March 29, 1949. A. PEET 1,465,697

GAS-FIRED WATER HEATER Filed Sept. 28, 1944 9 SheetsSheet l 7% 4%LMZL7 QM A itorneys March 29, 1949. A. PEET GAS-FIRED WATER HEATER 9 Sheets-Shet 5 Filed Sept. 28, 1944 Fla. 3'.

7 M 61 MA? A ltorneys arch 29 1949. A. PEET 7 GAS-FIRED WATER HEATER Filed. Sept. 28 1944 9 Sheets-Sheet 4 A ttomeyg;

March 29, 1949.

Filed Sept. 28, 19 14 A. PEET 2,465,697

GAs-FiRED WATER HEATER 9 Shee ts-Sheet 7 Inventor ai mw e2 A ttorneyS "March 29, 1949. A. PEET GAS-"FIRED WATER HEATER 9 Sheets-Sheet 8 Filed Sept. 28, 1944 March 29, 1949. A. PEET 2,465,697

GAS-FIRED WATER HEATER Filed Sept. 28,. 1944 9 Sheets-Sheet 9 FlGlS. 29 3O Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE GAS-FIRED WATER HEATER Alexander Peet, Luton, England Application September 28, 1944, Serial No. 556,203 In Great Britain October 23, 1943 Claims. 1

This invention has reference to gas-fired water heating apparatus adapted to give a rapid or almost instantaneous hot water supply and of the kind in which a self-closing gas valve regulates the gas supply to the burner and is automatically opened by pressure created by the flow of water through the water heating system.

According to my invention the automatic gas valve is controlled by a piston or other pressureresponsive member which is responsive to water pressure generated in a chamber interposed between the water inlet to the heater and the water heating system, the water pressure being generated in the chamber only when water flows through the heating system.

The required Water pressure in the chamber is preferably created by restricting the water flow from the chamber to the water heating system. This may be attained by the provision of a restricted orifice or constriction between the chamber and the heating system. The restriction should be of such an area that, together with the fluid friction losses through the remainder of the apparatus, the pressure created in the piston chamber will actuate the piston or other pressure-responsive member to open the gas valve when the water is turned on.

The gas valve is controlled by differential water pressure on opposite sides of a piston, diaphragm, or other pressure-responsive member in a chamber which is located at the inlet side of the water heating system, and the water control valve or outlet tap is preferably located at the outlet side of the said water heating system, the arrangement being such that, when the water outlet tap is closed, the pressures on opposite sides of the pressure-responsive member balance each other and permit the gas valve to close under the action of a closing spring (or by gravity), and when the water outlet tap is opened, a pressure diiierence is created on opposite sides of the pressureresponsive member, causing the gas valve to open. If the water tap is fitted at the outlet side of the water heating system, there is little or no possibility of the water dripping when the tap is closed. Moreover, the water heating system remains completely filled with water at the normal mains pressure.

The present invention further consists in the provision of a readily removable automatic gas valve controlling unit comprising a diflerential pressure chamber and piston or other pressureresponsive member, enabling the gas valve controlling unit to be replaced by one having a larger or smaller piston or pressure-responsive member to suit the water supply pressure at the place of installation of the heater.

My invention also includes means for creating the pressure difierence on opposite sides of the piston or other pressure-responsive member comprising a Venturi tube connecting the space at one sid of the said member with the inlet end of the water heating system, the space at the other side of the said member communicating with the throat of the Venturi tube where a reduced pressure occurs during the water flow.

The automatic gas valve controlling unit may also include a water pressure regulator or governor for regulating the flow of water into the water pressure chamber according to changes in the pressure and water flow, thus controlling the movement of the pressure-responsive member and regulating the degree of opening of the automatic gas valve. The water pressure regulator or governor may compris an apertured disc through which the water flows to one side of the pressure responsive member, the rate of water flow through the disc being controlled by a throttle valve movable with the pressure-responsive member.

The water heating system may comprise a circuitous water heating pipe or coil enclosed in a heater casing surrounding a gas burner of any suitable type which preferably includes a thermostatically-controlled safety pilot light.

The gas-fired water heater of the present invention is of compact design and is preferably constructed and arranged to enable the gas and water sections to be readil dissembled for cleaning, examination or repair.

In order that the invention may be more clearly understood, referenc is hereinafter made to the accompanying explanatory drawings whereon:

Fig. 1 is a view of the heater showing the casing in section and showing the interior construction in side elevation.

Fig. 2 is a sectional elevation through the gas and water sections.

Fig. 3 is a sectional plan view taken substantially on the zig-zag line 3-3 in Fig. 1.

Fig. 4 is a sectional view on the zig-zag line 4-4 in Fig. 2.

Fig. 5 is a fragmentary sectional view on the bent line 55 in Figs. 3 and 6.

Fig. 6 is a cross-sectional View of the casting only, taken on the line 6-6 of Fig. 5.

Fig. 7 is a sectional elevation showing a modified construction of the gas and water sections, the section being taken on the line 1-4 in Fig. 9.

Fig. 8 is a sectional view on the line 8.8 in 9.

Fig. 9 is a plan View of the construction shown in Figs. '7 and 8, but with the burner removed.

Fig. 10 (sheet is a cross-sectional view taken on the line I0H) in Fig. 7 showing the casting only.

Fig. 11 is a diagrammatic illustration of the gas and water passages of the heater shown in Fig. 2.

Fig. 12 is asimilar diagrammatic representation of the gas and water passages of the heater shown in Fig. 9. The arrows show the direction of flow Water is supplied to the heater through a supply pipe 6 and after passing through the water section 5 and through the branch 3 is heated in the pipe coil 2 by the products of combustion from a gas burner l. The water heated in the pipe coil 2 passes by way of the branch into the water section 5 and is finally discharged through an outlet spout 8.

The gas is supplied to the burner by a gas supply pipe 9 which is coupled to an elbow Ill. The gas after passing through a governor ,II is controlled by a manually-operated gas valve [2 before reaching an automatic gas valve l3- contained in a casting I l hereinafter called the gas section. The automatic gas valve I3 is normally pressed down on to its valve seat by a spring I5. When the valve i3 is automatically lifted by Water pressure, as hereinafter described, gas rises into a tube it which is coupled to a central tubular vertical extension ll of the gas section Hi. The tube it forms a support for the burner 'l and houses a safety valve [8 which is controlled-in known manner by a bent bimetallic strip 19 which is under the influence of a pilot jet 20 to which gas is constantly supplied by way of a pilot jet tube 2! except when the gas valve I2 is moved to completely out off the gas supply. One end of the bimetallic strip i9 is fixed to a central boss 22 on the burner l and the other end is forked to engage between a pair of collars 23 on the spindle 2d of the safety valve 18. ,Should the gas supply fail for any reason, causing the pilot jet 2i] to be extinguished, the bimetallic strip I9 opens out and lifts the spindle 24, in known manner, thus closing the safety valve l8 on to a valve seat 25 and cutting off the supply of gas to the burner.

On reference to Figs. 2 and 4., it will be seen that the gas governor H comprises a chamber 26 in which is a horizontal diaphragm 21 held in position on an internal shoulder by a spring 28. Below the diaphragm 2! and loosely resting by legs 29 on the base of the chamber 26 is alight diaphragm 3B of smaller diameter than the chamber 26, see also Fig. 15. When gas enters through the elbow Ill, it passes through a filter 3| and around the edges of diaphragm 3E] and through a central port 32 in the spring-pressed diaphragm 21. A depending flange 33 around the port 32 serves to limit upward movement of diaphragm and to prevent gas passing through port-32 in the event ofa sudden inrush of gas.

An outlet branch 34 on the governor chamber 2 has screw-threaded connection with a gas inlet branch 35 in the gas section 14. Passages 36 are formed in the casting l4, these passages being cored or drilled out (as seen in Fig. 4) on both sides of a central portion 3'! through which passes the stem 38 of the automatic valve l3. The passages 36 connect the inlet branch 35 to lateral .ports 39 in the main gas valve I2 which has an axial passage to connecting the ports 39 to a chamber ll formed in the centre of the gas secntion, communication between the chamber l and thezburner supporting tube it being controlled by the automatic valve l3. As shown, the main gas an indicator dial 43.

The heater shown in Figs. 1 to 6 has the gas burner." l; detachably mounted by means of studs M upon the gas section [4 which is detachably surmounted upon the Water section 5. The.auto- ,matic gas supply valve l3 to the burner is, centrally and vertically disposed in the gas section above a vertically movable controlling piston 4'! Lin the water section. The gas section 14 may be removed without disturbing the water section 5, it being understoodof coursethat .the g as supply main must be uncoupled from thel gas section at the front thereof, the gas passing from the governor l l at the back of the gas sectionto the gas tap [2 through the passagesiafiiormedin the gas section around, the vertically and centrally disposed automatic gas valve 13. The gas from .the main supply pipe passes through the governor H detachably fitted to the back ,of the gas section i l.

At the underside of the gas section l4is a valve guide 58. The water section 5, is fitted inits upper part with astuffing gland A5 for a spindle 56, the upper end of which touches thelower end of valve stem 38 and the lower end of which rests on the piston 41 movable in a piston chamber 38. Screw-threaded into or otherwise attached to the underside of'the piston 41 the stem 53 of a governor valve 50. The stem..49 passes through a central port Si in a diaphragm 52 which is pressed upwards againstan internal shoulder 53 by a screw-threaded ring .53a,..a filter 5 being interposed betweendiaphragmjl and ring 53a located in a space .55 in thc;low,er part of the water section. The governor. valve controls the flow of water through the port 15!. The underside of the water sectionis closed bya detachable cover 56 havingan. outlet passage v5! which communicates with the outlet spout ,8 swivel-mounted in the stufling gland 59. 7

Water from the main supply pipev .6, which is coupled to an inlet branch 6| .on the water section, flows through a passagejfi ,intothe space and passing through theportjl indiaphragm 52 enters a space 50 at the underside of piston 4i. Rotatable in a lateral extension 53 of..the casting 5 is a water control tap comprising ..a tapered plug 64 rotated bythe spindle 65 vof a knob 5t. 'The spindle 65 passesthrough a stufiing gland t! and the plug M has adoubie conical axial passage through it which .formsa Venturi passage 63 connecting the spacefill with. an, annular space 68 at theouterend of plugt l. Space 69 communicates withtheouter end of alongitudinal groove 10 cut in the side ,ofplug 5%, and the inner end of groove It cornmun icatesbyway of a passage 1| inca t ne .5 itht espace .69.

Passage II and groove in form a passage which bye-passes Venturi passage 68. The annular space 69 also communicates with outlet branch :5 to heater pipe 2. It will be apparent therefore that water from space 58 beneath piston ll can flow to the heater pipe 2 either through Venturi passage 68 or bye-pass passages Ii, iii. In the region of the throat of the Venturi passage, radial holes E2 in the plug fi l communicate with an annular groove it around the plug. Annular groove 73 communicates with a lateral passage Id which opens out into a chamber in which is fitted a hollow check valve 76 which is axially and easily movable in chamber I5. One end of valve 16 has a small central bore TI and is adapted to seat in a seating ring it. The outer end of chamber '55 is sealed by a plug '19 and a vertical passage 88 connects chamber '55 with the space 43 above piston ll.

The piston is preferably made of a hard rubber compound or of a metallic or non-metallic or composite material which will work freely in the piston chamber at any water temperature.

The controlling piston 37 is subjected to differential pressure on opposite sides thereof to control the opening of the gas valve l3 during flow of water through the heater, and the arrangement is such that by removal of the bottom cap or cover 56, which includes the water discharge passage 3, access may be had to the piston 4.! without removing the gas or water sections.

The water tap t l having the control knob acts as a water temperature selector tap and is arranged horizontally on the water section at the front thereof, this water tap incorporating the Venturi passage fit, one end of which communicates with the chamber 58 in which the piston ll is vertically movable, said chamber 53% being in communication with the water inlet GI, and the throat of the Venturi passage being in communication with the space at above said piston, thereby to create a reduced pressure above the piston :il' when water flows through the Venturi passage 68, which delivers the water through the outlet branch 3 in the tap casing to the water heater pip or coil 2. Temperature control of the water is attained by the provision of the bye-pass passage i9, HI between the outlet port from said selector tap and the lower part 6i? of the piston chamber, the flow through said bye-pass passage III, I! being regulated by adjustment of said selector tap, to regulate the flow of water through the heater pipe or coil 2.

Th gas tap and water temperature selector tap, as shown, are preferably in the form of rotary plug taps working in barrels forming lateral extensions of the gas and water sections respectively. This arrangement permits of removal of the plug taps for inspection and cleaning, without disturbing the gas and water sections. Moreover, as the Venturi passage is formed in the plug of the water tap 8 3, removal of the latter withdraws the Venturi passage for inspection and cleaning if necessary.

The axially-movable check valve i6 is adapted to seat itself and restrict communication between the Venturi passage 68 and the upper part 48 of the piston chamber when water flows through the system, thus retarding upward movement of the piston 41 and consequent opening of the automatic gas valve I3. The aforesaid check valve 16 is unseated by expulsion of water from the upper part as of the pis on chamber when the automatic gas valve I3 closes under the action of its closing spring I 5 (or by gravity), thus rap- III idly establishes equlibrium on opposite sides of the piston 48 and quick closing of the automatic gas valve I3 when Water ceases to flow through the heater. One or more holes I62 (Fig. 2) are provided in the castings 5 and I4 where they meet, in order that water or gas leaking into the space between the two castings can escape. The Water flow is controlled by the provision of an outflow tap 8| between the outflow end of the heater pipe or coil and the discharge spout 8 which is swivel-mounted on the bottom cap or cover 56 of the water section. A cold water supply tap 32 is preferably also provided for supplying cold water direct to the discharge spout 8 from the water inlet main 6, when required.

A water pressure governor is preferably combined with the gas valve controlling piston 41. For this purpose the ingress of water into the space 60 beneath the said piston and from thence through the Venturi passage 68 or bye-pass passage ?0, II to the heater pipe or coil is governed by passage through the central port 5i in the diaphragm 52 which closes the underside of the piston chamber 60, the port 5I being controlled by the throttle valve 5i) carried at the end of the stem 49 attached to the piston 41, so that lifting of the piston 4'! throttles the flow of water through the diaphragm 52.

Access to the gas and water sections of the heater is afforded by the provision of a removable bottom cover 83 fitted to the base of the outer shell or casing.

As shown in Fig. 1, the heating pipe 2 is coiled around an inner metallic shell 85 fitted in its upper portion with a finned heat exchanger 85 from which the products of combustion discharge through an opening 87 in a cover 88. The pipe coil 2 is preferably made in two lengths brazed at 89 to a return bend and held apart by a metal clip H5. Spring clips I52, one of which is shown in Fig. 1, serve to position the pipe coil 2 and inner shell 85 within the outer casing I.

When only cold water is required, the cold water tapEZ is opened and cold water flows from cold water inlet connection BI into space 55 and through a passage I58 into the casing of the tap 82 and from thence through a radial passage I59 in cover 56 to main outlet 57.

When hot water is required, hot water tap Si is opened and hot water from the heating pipe coil 2 flows through return connection 4 and a passage ISIl to the casing of hot water tap SI and from thence through a radial passage IBI to the main outlet 51.

The water flow connections will now be described: W'ater enters pipe 5 from a water supply main and flows through pipe SI and passage 52 to space 55. If cold water tap connection 82 is open, cold water flows from space 55 through passage I58 to radial passage I59 to main outlet 5'1 and outlet spout 8. If hot Water tap connection BI is open, cold water from space 55 rises through filter 5 3 and through port 5! into space til below piston All. From space 66, the water flows through Venturi passage 68 to outlet branch 3 (Fig. 3) connected to inlet end of heater pipe coil 2. The water heated therein returns to branch l (Fig. 6) and flows through passage I68 and radial passage IBI to main outlet 5'! and outlet spout 8. If both hot and cold taps are open, hot water from passage ISI and cold water from passage I59 mix in main outlet 51.

When water flows through Venturi 68, it creates a reduced pressure at radial orifices lg and annular groove 13. This causes a suction in pasmanner sage 1.4, causingv check val-volt to'close on seat 18;. .Thesuction through small bore ll of :valve 16 :slowly; draws water through passage fit "from the space' llB above piston til to open gas valve it.

The temperature of the outflowing hot water canube'reduced by 'opening bye-pass valve ,64 to cause waterto flow from space 59 direct to heater pipe icoil connection 3 through bye-pass passages .ll, 10 without passing through Venturi passage The gas supply is as follows: Gas main S supplies ,gasthrough bend iii to underside of.:-,diaphragmtll, around which the gas flows, to'pass through port 32 into governor chamber 25. From thence-gas flows throu h passages 35 (Fig, l) .tocradial holes :39 and axial hole 38 in main gas valveplug 12. From axial hole ii? it'passes into central chamber ll and to burner I when auto- ,matic gas valve 13 is open. Main gas valve plug .l zlcanwbe-turned sothat radial holes 39 are out ofcregister with passages 36, in which case no .gas can pass to the burner.

Gas valve plug '32 is constructed in generally well known manner to supply gas to pilotburner 2! except when the gas-valve'mandle 42 is turned into the fully-ch" :position.

Referring now to Figs. 7-10 Fig. 12 of the drawings, which illustrate an alternative form of the :gas and water sections, the burner l is detachably-mountedby a coupling nut 9% upon a casing :9! which encloses a horizontally mounted "ing through a port -99 from the main gas valve.

When'the 'gas lifts the bell 98, the gas'passes through angannular space H393 aroundthe bell and through a port till above andcontrolled by the-bell, the port H3! opening into a chamber 102 which communicates through a horizontal passage 103 with a chamber let, the end of which is adapted to be closed by the automatic gas valve 92.

The'main gas valve 95 is of the known rotary plug type in which a radial outlet passage tilt in the valve plug registers in the open position with the-port'tfi leading to the gas governor. In order to-control the arnountto which the port 99 can be uncovered, and thus adjust the valve 95 to local conditions of mains gas pressure and gas calorific value, a circumferential groove tilt maybe-provided partly around the plug valve 96,011 end of this groove being adapted to abut against a tangentially disposed adjustable stud or'abutment ill! fitted into the plug barrel ll'i.

The main valve casing 94 is mounted upona water section lil 'to which it is detachably secured by bolts we. The water section comprises a'main water inlet connection Hi3 and passageways 8% and 'l H leading to the casing H2 oi a coldwater tap i It which controls communication-betweenthepassageway ill and a passageway l Mdeading to a water outlet M5 to which a swan-neckeoutlet spout (such as 8 in Figs. 1-4) may be fitted. The water section l 53 has branch H'l for connection to the return from a water heating pipe (not shown), which may be-sirnilar tothe pipe-2 ofFig. l. The branch 5 ll communicatesbywayof passages H8 and HQ with the casing IZUofahot-water control tap l'2l which.

controls theeflow ofshot water from thepassage ltllito a passageway l22leading to the water outlet i l-l5 'A'bye-pass valve I23 in the water section has a'radial hole l23awhich controls communication between the main water inlet connection :Hllsand an outlet branch we (see Fig. 13) on the casing l25 of the valve 523, theoutlet branch l241 being coupled to a bye-pass pipe 126 by meansnof \acoupling nut 131. Detachably mountedlwat one sidezof the main valvecasing M and in axialxalignment with the automatic gas valve 9-2 is a gas valve controlling unit which comprises apistonchamber l2! having a piston lEB movable therein in axial alignment with the stemtl-ZS of the valve 92 and adapted to actuate the latter through a rod 430 movable through a stufiingr -gland' l3l.. The piston E28 is of the skirted typeand the space I32 enclosed by the piston skirt is substantially closed by a diaphragm l3'3-havinga central port 53% through which-water can enter the space 232 from a'space 35 behind; the diaphragm i333, said space H5 communicatin with a Water passage 536-111 the lower wall of piston chamber 521. Water from the main inlet Hilafter .iiowing through passageway 84, in addition to flowing through passageway I ll totap H3 also passes upwards through. an outlet branch 155 which is coupled by a coupling nut i lto' a pipe -i38 which opens into the waterpassage lat. The back of the space liiobehindthe diaphragm I33 is closed by aicover 139 for the end of the piston .cham ber. The central port lt l in the diaphragm 433 is controlled'by athrottle valve or governor valve l lil'carriedby a stem Ml which passes through the diaphragm 133 and is secured to the piston .528. A bent platespring M2 makes contact with the end cover I39, diaphragm i355 and valve lit to hold the diaphragm H3 in position. Above the .piston chamber 12'! is a Venturi ube M3 which forms part of casting m. The end Hit of the Venturi tubecommunicates with the space l32 behind the piston 123 by way of a passage l58 sealed at its outer end by plug H53, and the other end of the Venturi tube communicates with branchv l lfiuforconneetion to the inlet end of the water. heating pipe; VVhen the hot water tap it! is opened, hot water enters the tap at Hi from the heating pipe not shown and passes to water outletvlld through passages H8 and 122. Cold water enteringr the apparatus at llil, flows throughpassagesat and pipe its into passageway 535 and throughan annular'port 5 35 into the space 135'- behind diaphragm E33, thence through port l3 lcontrolled .b-y governor valve Hill into space I32 behind piston E28. From thence it flows through passageiws into one .end of the- Venturi tube M3, flowing therethrough intobranch ME-connected to the inlet end of the-water heatingipipe. The bye-pass water tap i723 providesa direct fiow of water from the water inlet connection-Htthrough bye-pass p-ipe I26 to the branch I l-5 leading to the water heating pipe, so that water may pass to the heating pipe without passing through the piston chamber, thus enablingrthe outflow temperature of the water to =be-regu1ated.-

In-order to -establish a'difierence of pressure on opposite'sides-of the piston till; when the hot water- -tapilfil is opened and water commences to flow throughnthewater heating pipe, a space 1'41 in -front-of the pistoncommunicates through an orifice--|32awithrthe space E32 behind the -pis-tcn .at the-:throat of the -"Venturitube 6143 through a :ltransrer -rpassage l 48 --Whi'c-hi is oontrolled by an automatic check valve I49 arranged to retard the flow of'water to the Venturi tube from the space I l-I and to accelerate the flow in the reverse direction. The purpose of this check valve is to check the outward movement of the piston I28 and consequently retard the opening of the automatic gas valve 92 when the water is turned on at the hot water tap. Conversely, when the hot water tap is turned on, it is desirable that the spring-closed automatic gas valve 92 should close rapidly and this is permitted by reason of the fact that the automatic check valve I49 permits a rapid return flow of water from the space I4! in front of the piston to the space I32 behind the piston. The automatic check valve I 49 is in the form of a hollow plug valve which is an easy fit in the transfer passage $48 and is externally grooved to allow water to flow freely around it. The bore of the Valve M9 is small and the end of the valve is tapered as shown to seat on a Valve seat I50 in the transfer passage I48. When the hot water tap is turned on, the water flow through the Venturi tube Hi3 causes a reduction of pressure in the tranfer passa I43, so that the check valve 149 is seated and water can only flow through the bore of the check valve from the space Ml in front of the piston, thus retarding outward movement of the piston I 28 and opening of the automatic gas valve 92 which regulates the supply to the burner. When the hot water tap is turned off, the pressure of the closing spring 93 on the automatic gas valve 92 returns the piston H8 in its chamber and the rush of water from the space I32 behind the piston forces the automatic check valve I49 off its seat, thus allowing the water to flow rapidly to the space I41 in front of the piston An abutment screw I51 limits the travel of the check valve.

When only cold water is required, the cold water tap H3 is opened, water flowing then directly from the main water inlet connection i It through passages 84, HI and H4 to the water outlet II5 without passing through the water heating pipe.

When hot water is required, the hot water tap MI is opened, whereupon the water already in the water heating pipe escapes through the water outlet I I5 and fresh water enters the water heating pipe by way of the piston chamber I32 and U Venturi tube H33 as already described.

If the outflow temperature of the water is to be reduced, the bye-pass water valve I23 can be opened to supply water direct to the water heating pipe without passing through the piston chamber or gas valve controlling unit, (as already described), the volume of water passed by the bye-pass valve being regulated according to the desired eilluent temperature.

As the gas valves 92 and 95 are horizontally mounted in the gas valve body, they are readily accessible for inspection or cleaning without necessitating removal of the gas burner,

It is to be understood that my invention is not limited to the details of construction hereinbefore described with reference to the accompanying drawings, inasmuch as subordinate details of the construction are capable of modification or variation within the scope of the invention defined in the appended claims. For example, the piston 4? or I28 may be replaced by a flexible diaphragm or other pressure-responsive member.

I claim:

1. Water heating apparatus comprising a water chamber, a cold water inlet to said chamber, a water outlet passage leading out from said chamber, a rotary plug valve in said outlet passage, a Venturi passage formed axially in said plug valve, a housing for said valve, an outlet port in said housing, said outlet port communicating with one end of said Venturi passage, a water heating pipe system connected at one end to said outlet port, a discharge passage leading from the other end of said pipe system, a water tap in said discharge passage, a pressure-responsive member in said chamber, the space behind said member being open to the cold water inlet and to said Venturi passage, a bye-pass passage connecting the space behind said member with a recess in said plug valve, said recess establishing communication one position of said valve with the outlet port in said housing, a water passage conmeeting the throat of the Venturi passage with the water chamber space in front of said mem her, a gas burner arranged to heat said pipe system, a self-closing valve adapted to regulate the gas supply to said burner, and operative means between said member and said self-closing valve for opening the latter by displacement of said member under reduction of the water pressure in the space in front of said member.

2. Gas-fired water heating apparatus including a water heating pipe system, a gas burner arranged to heat said system, a self-closing gas valve for regulating the burner, a differential pressure chamber, a pressure-responsive member movable in said chamber and arranged to control said gas valve, said member separating said chamber into primary and secondary compartments, a cold water inlet connection to the primary compartment, a rotary valve housing, a rotary valve in said housing, said valve having a double conical passage therein communicating at one end with said primary compartment and at its other end with the heating pipe system, a bye-pass passage between said valve and valve housing, the flow through said bye-pass passage being controlled by angular adjustment of said valve, and a transfer passage connecting the neck of said double conical passage to said secondary compartment.

3. Apparatus according to claim 2 having means for manually effecting angular adjustment of the rotary valve.

4. Apparatus according to claim 2 wherein the rotary valve is a hollow plug having the double conical passage formed axially therein.

5. Apparatus according to claim 2 wherein the rotary valve is of the plug type having the double conical passage formed axially therein, said valve having a recess in the side thereof which communicates with an outlet to the heating pipe system, and the bye-pass passage communicating with an inlet port in the valve housing, said inlet port opening into said recess on corresponding adjustment of said valve.

ALEXANDER PEET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 681,018 Crocker Aug. 20, 1901 799,670 Reynolds Sept. 19, 1905 1,114,877 Goreau Oct. 27, 1914 (Other references on following page) 

